When food granules of pet food are coated with oils and fats, it is possible to increase the calories of the pet food. Further, it is possible to improve the biting property (palatability) of a pet.
As a method of coating food granules with oils and fats, a vacuum coating method of reducing the pressure applied to food granules in a state in which the food granules are in contact with oils and fats is known.
For example, beef tallow is used as the oils and fats for coating food granules and used by being heated at 40° C. to 50° C. in advance to prepare the beef tallow in a liquid state.
PTL 1 describes a method of coating food granules baked in a furnace (190° C. to 210° C.) provided with a ceramic heater with oils and fats according to a vacuum coating method. In this method, since the baked food granules are cooled while being conveyed by a net conveyor, food granules are coated with oils and fats by charging the food granules into a pot, heating the food granules to 40° C. or higher, adding oils and fats to the pot, reducing the pressure in the pot, and gradually returning the pressure to the atmospheric pressure. Further, PTL 1 describes that solidification of oils and fats can be prevented by heating the food granules to 40° C. before oils and fats are added.